Heat exchanger



K. H. FLINT HEAT EXCHANGER Oct. 14, 1952 2 SHEETS-SHEET l Filed Dec. 14, 1949 T ll K. H. FLlNT HEAT EXCHANGER Oct. 14, 1952 2 SHEETS--SHEET 2 Filed Dec. 14, 1949 Patented Oct. 14, 1952 HEAT EXCHANGER y Kendall H. Flint, Kalamazoo, Mich., assignor to Borg-Warner Corporation, Chicago,

poration of Illinois 1 Ill., a cor- Application December 14) 1949,v Serial No. 132,938

'This invention relates in'generalr'to. improveconcime. (or 257-174) device seeks tol employ conventionalparts wherever necessary and possible, thereby to effect a ments in air heating-furnaces, and it has particul lar reference to .the'provision of an improved heat exchanger and its organization in air heating. 1 vIS ciency of the'products of combustion will be atfurnaces in such manner that the maximum' ef-j tained.'f v y lHeretfore,in earlier prior art air heating-furnace constructions the heat exchangers were formed of cast 'iron 'or the like which obviouslyA further substantial reduction. in the cost over was an expensive construction* With the advent j of formed steel, manylof the disadvantages ofthe y cast type heat` exchanger were overcome because` new shapes heretofore .found `impossible were formed. :to increase vthe'. efliciency of the heat exchangers. It-has longL been recognized that one of the very*importantgfactorszin the construction of a proper heat exchanger is that of maintainingt y the products of combustion Within the heatzex-I changer as long as rpossible and also to provide!" an even and elective .distribution of heat through the yentire heatl exchange 'surfaces of 'the heat exchanger. 1

In order to accomplish and give proper consideration to the aforementioned important fac,-

ftors, prior art constructions defined many different `shapes providing. serpentine passageways,

fluted formations, bailles, and the like, each being of expensive construction and, although increasing vthe efficiency of the heat exchanger to a`degrec, were decientiin obtainingthe maximum exchange of heat between the products of comy bustion and the heat exchange surfaces ofthe heat exchanger. f. :It isrecognized that in the prior art numerous attempts havefbeen Amade to provide a heat ex'-r changer of ythis 'general class and efforts have;l

been madet overcomethe various deficienciesy found in such prior art structures, but to the best of the applicantsrknowledge the prior art structures have had only limited success and have been accordedonly limited commercial recognition. It is believed that this fact results from apparentdeciencies of the prior art structures, their nonadaptability for universal application and their expensive construction which so greatly Y increased the costas to seriously handicap sales acceptance.

The present improvements in heat exchangers arer directed to simplify thelrvconstruction and their mode of operation, and also to provide a heat exchanger which may readily and conven- -iently be employed universally( to various types and sizes of air heating furnaces presently being commercially exploited.l Moreover, the presentv the prevailingftypes of heat exchangers presently' being employed.

According to one aspect of the present invention the desired result may `beobtained by utilizing a heat' .exchanger formed of steel to dene chambers through which products of combustion may advantageously'flow, said chambers being particularly characterized in that the side walls thereof aretapered so that thel top opening is smaller than theV bottom inlet opening and said side walls being provided with indentations arranged Vin a manner so thatV the products of combustion flowing through the chamber Will define a serpentine path, thereby to increase the tendency toward a scrubbing action.between the productsofy combustion and the side walls of the heat exchanger.A I

Accordingly, an object and accomplishment of :the invention is to provide a heat exchanger formedofwelded `steel to define a plurality of 'thereby obtaining a. scrubbing action between chambers vhaving upwardly tapering side Walls, thereby progressively reducing the area inside the f nue chamber, whereby therel is maintaineda constant density of gases under a reducing flue tempera-ture and, therefore, more molecules come in contacty with the heating surfaces than would come in Contactin a straight iiue,vthe invention f being particularly characterized in 'that the products of combustion passing through the chaml ber will actually define a tapered path comparable to thatden'ed byv the upwardly tapering side walls of theichambe'ras taught by this invention,

.fthe products of combustion and the upwardly tapering side Walls of the chamber at a point wherethere will be the greatest exchange of heat between-these elements. f

Another vobject andaccomplishment of the inteachings of this invention.

vention is to provide an improved heat rexchanger as contemplated hereinand which may be manufactured i'n segments,- ther'eby to increasel the versatility 'of the 4assembled heat exchanger in that various sizes-land arrangements maybe 'attained to facilitate universal application of the Another object and accomplishment ofjthe invention isvto provide an improved heat exchanger 4 by co-relating and especially designingv the'various elements 'thereofy whereby there' shall be such cooperation between said improvedelenients aswill b st serve the purpose of providing'an efficient heat exchanger-'capable of being manu- `in ,the claims.

factured at low cost and yet giving maximum of satisfactory service in use.

The invention seeks, as a further object and accomplishment, to provide a heat exchanger and an arrangement thereof as contemplated herein and particularly characterized by an arrangement of parts to more advantageously and satisfactorily perform theV functions required -zofffit and adapted to provide a compact unit which will successfully combine the factors of structural simplicity and durability, and yet be economicalv to manufacture.

A further object and accomplishment Aofthe herein, and in the drawings like reference characters identify the same parts in the several views.

As one possible example of advantageous employment of the heat exchanger and the arrangement thereof, reference is made to the drawings, particularly Fig. 1, wherein there is illustrated the heat exchanger with which the present in- -jfvention isvparticularly;'concerned and; designated inits entirety bythe numeral" 2D aseb'eing operainvention is to provide a new and'irnpro'veld form.- l of heat exchanger which `is'adapted to vbe ecoe- J o nomically manufactured, and which is so designed -as to permit the manufactureV Iandwassembly thereof, in accordance with present day large scale mass production manufacturing vfully described, and, fasmore particularly pointed out in the lappended claims. I

. 1 Vwith-.the above and other inciden-tai objects in View, the invention has other Ymarked improvementsand `superiorities which` radically .dis- Atinguishit from presently known structures, these improvements in the invention residing'fin. the...

novel-construction and cooperative function `of h the :parts thereof, the combination oftheparts ...and thel arrangement thereof asillustratediin .the .drawing and which Will-'be more vfullydescribed hereinafter and vIn-lthe. accompanying7I drawing onn'which `there isshown a preferred embodimentof therinven- .tion,,v l"Fig l; is aside eleva'tional-viewof a heatex-f.A .changer assembly embodying the features offthe -present invention;

Fig. 2' is an. elevational View of thehea--t exchangerdepicte'din Fig. 1;.

-Fig.,-3 is an elevational View of the heat -exchanger depicted in Fig. 2 and having portions .thereof shown in section taken substantially on .the plane. ofthe line 3--3 .in--Fig.2 =in .order to '.,clearlyillustrate the constructiongthereof; l

, f .Figi 4 is-asectional viewofza portion 4of .thejhea exchanger depicted .in Fig.` 2 andbeing itaken Fig. 5is a sectional View of one element ofthe heat exchanger depicted in Figs. 1,andr2 and illustrating the openedv position of said L element orV flat shallowsubstantially U.-shaped .channel t configuration .after formation. from a flat vsteel blank and before .being bent into shapei. e. in a substantially U-shaped configuration to define one element .of the heat ,exchanger as. A depicted -in -Fig..3;and. Y l .n

Fig. 6 diagrammatically' illustrates Athe .theoretical aspects relating .to the `tapered fluefconstruction formi-ng an p important feature of the 1 i .1eSe.I1tirwcnicn` 1 The drawings 'are to.be understood to be more or less of a schematic character forVY-tlie purpose of illustrating and ydisclosing atypicalor pre- .ftrred `form of. the improvements. eontemplated particularly: pointed. out

tively associated, for example, with a heating aplparatus supplied with a fiuid fuel, such as gas, .emanatng from gas jets or burners designated i` their entirety by the letter A, and a collection '-lbo'xdesignated-in. its entirety by Ithe letter B and disposed'abovesaid heat exchanger 20 in a positibnto Areceive"the expanded products of comybustion from .the heat exchanger per se, thereby.

to distribute the same to a suitable flue.

l-"'-Ihe -ga's burners A may be of conventional construction and arranged so that each segment of the neatrexchanger .20 will havey operativelyl dis- Y.posedftherebelow one unit of; said gasburners in amanner so thatthe products of combustion willbe received into the element. Y, .Y

i 1 Suflce it -to say, sincethe inventionis notparticularly concerned with the'precise construction of the gas burners and the other associated lparts of.v the air: heating furnace, they will not be fur- Yother ldescribed in.. detail, vandfit :is deemedpsu- S.tained .to show only :portions thereof adjacent cient for all. intentionsfandpurposes herein con- Ato 'andi cooperating with-the heatexchanger and the arrangement .thereof as contemplated herein: It. is to be understood that details of con- .struction-of such air heating furnaces with which .the heat.V exchanger arrangement contemplated 'herein `may iadvantageously'be.- employed, and/or theirassociated parts, may-be.,rnodified to suit particular conditions orto-satisfy the engineer- 'ing genius of various'manufacturers, and do not .wish to be limited to the precise construction rof 'these elements; as setforthexcept Where such construction particularly concerns theinvention contemplated herein.

-1 vHavingcthus described, .by way of example, a

possiblexadaptation 1of.` the heat exchanger and the. arrangement-thereof Agenerally indicated at 2B land.ascontemplated .herein,;.and having described thel general environment surrounding the adaptation,-thezspecic construction and ,cooperatiyeffunctions. of.v theA parts. of said lheat ex- .changer with which vthe vpresent invention is particularly-concerned, Iwill now lbe described in detail.

.-.Referring, now-to thedrawings, it willbe-,observed fromthe .side views shown in Fgsll.and A3,.'thatI have. illustrated a four-sectionr heater, YbutaJ-Lfwish'- itto be :understood that while the ,'multiplication of similar .unitsxfor the production of fa multiplev section heater lis an important ifea- .ture :ofthe-invention, so faras-certain features .ofuthe'invvention areconcerneol, the heater may l consist-,fof `a singlesection and that the multiple `rsection heater. may bacomp'osed of two sections. three sections, l fo1 1lr. sections as hereinvlillustratd, y :nl-.r-noreifgdesired.: .5 Injtheexemplary'embodiment of the invention depicted in' Figs. 1, 2, 3, 4, and 5, 'the-heater- .changer 2i!v with whichzthe present invention is l particularly: ,concerned .comprises in general, ,a Jserieslofj opstanding tubes 30, 3 |,32 and 3 3. formed of pressed steel elements and-respectively `having flangesd,35,136,537which are'welded by any sl'table approvedpractice to secure theseele- :62 and G3. ymember 68, there is providedflanges 64 and '.65 Vwhich complete the structural definition of this :tube 33.,

Since all of the tubes areof-similar-construc- Ation it is deemed sufficient for all intentions and purposes herein contained to describe only two of them. Accordingly, particularaattention isinvited to the formation of thetubes-32 and 33.

Advertingto Fig. 5 it can be seen that the elements forming a part of the heat exchanger 20 are formed in separate units orsubstantially U- shaped channels which are relatively shallow and 'relatively wide from a fiat steel blank tondeflne the shape as illustrated in Fig. 5. After the formation of the unit or channel, the legs 40 and 4I are bent -in the direction of the arrows, that is,

the channel is bent .back on itself in a U-shaped manner to substantially define a U-shaped configuration to a position indicated by the ydotted lines and so that the end portions or flanges Vll2` and 43 respectively of the legs 4o and 4l engage each other and are welded to define a unitof the heat exchanger 20. l

. It can be seen that the leg `lili is deformed to provide a plurality of inwardly extending indentations 45,v 4S, and 41 while the leg 4I is also deformed# to .provide a Vplurality of inwardly extending indentations 13, 49 and 50. tions, asclearly shown in the drawing, 'substantially meet the center line of the tube and pro- --vide an interruption to the upwardly flowing combustion gases While passing through the tubes in order to effectively and advantageously provide amore efficient scrubbing action between. the combustion gases and the heat exchange surfaces. This serpentine passage of the combustion gases throughthe tubes is defined'by the arrows .depicted in Fig. 3, and can readily be'seen to be provided within the tube by the successive alternation of the indentations on both Vwalls ofthe tube so as to be spaced from the opposing wall.

Having 4thus describedone unit of the heatexchanger 20,'particularattention isinv-ited to Figs. 3 and 5 which illustrate that necessary to have an end member, generally indicated by the ynumeral 60, which actually is one-half of a unit as disclosed inv Fig. 5 and more particularly defines a shape similar to that of the leg` 4I. Thus itz. can be seen that the end member 60 is also deformed to define `a plurality of indentations 6|, Moreover, at each vend of the. end

element.

'.Again adverting to Fig. 3, it can be seen that an element of the heat exchanger 20, as disclosed ,in'Fig 5 and when nally formed to assume its position as disclosed in Fig. 3, defines only one- ,half of the tube, it being necessary to assemble another like element in position to complete the tube formation. Accordingly, in Fig. 3,l the leg 40 denes only one-half of the tube 33 while the end member, when placed in position as Adisclosed in Fig. .3, will complete the formation of the .In rorder to provide proper spacing between the various` unitsjoiv the heat exchanger 20, therey are provided spacers 1li, 'H and12, each being a cuplike deformation extending inwardly of the walls of their respectively associated legs. VIn Fig. 3, in connection with the tube 33, it can be seen that lthe spacerl is arranged to engage l.the indentation 63 and thus substantially meetthe center Vline, of the tube while the spacer 12 forming .a

part vof theend member 60 is'arrangedzto engage vportions of the indentation 46 forming a part of the leg 40. This construction ismore clearly il- .-lustrated in Fig. 4 Awherein the lateral extent of These Vindentaf defined paths to the top of the tubes.

6 y, the l indentations .is illustrated. It can be seen that the findentations are stopped short 'at the ends of' the units as indicated at 15. Thespacers areacup-likev shaped in order to permit the combustiongases to pass through the tubesy in their When the units of the heat exchanger vare weldedintheir operative positions as illustrated in Fig. v3, itcan be'seen that the flanges disposed at the top and the bottom ofthe heat exchanger` units define a top wall 18 and a bottom wall 19, thereby sealing off the owof the combustion gases so that these combustion gases emanating from the heat elements Afwill iiow through the tubesand up to the collection'box B. A further a conventional tube having parallel upstanding sidewalls and 86. It hasbeen found that the density of combustion gases passing upwardly through a tube is proportional to the absolute temperature. it is obviousthat the temperature at the lowermost portion of vthe tube willjbe higher than thetemperature in the upper portion of the tube. Thus, by followingy this procedure it is also obvious that the density of the combustion gases, will be greater at :the lower portions of the tube and that the density of the combusf tion gases will be proportionally reduced as the temperature drops while the combustion gases move upwardly in the tube. Thus, by reducing the area inside the flue chamber by employment ofthe wedge-typel flue of the instant invention l therel is maintaineda constant density of gases under a reducing flue temperature and, therefore, more molecules come in contact with the heating surfaces than would come in contact in a straight flue. Accordingly, as illustrated in Fig. 6, the density of combustion gasesr will define approximately a taperedWedge-like lshape as diagrammatically illustrated'by the numeral 81. Thus, it can be seen that the density, or, in other words,

' the hottest portion, of the combustion gasespassing through the tube will be within the area defined by broken lines and designated by the numeral 81. In this connection, it is also important to note'that the hottest area would be within that portion defined by the lines B8 and 89. Thus, it is obvious that if the walls 85 and 86 would be movedginwardly to define a tapered formation and respectively lie in the same planes as the lines 88`and 89, the most efficient heat exchange would be accomplished. This, in thec'iry,` is vthe important feature of the subject invention. u

Therefore, the combination of the upwardly rtapering side walls of the respective units of the heat exchanger in combination with the functions-of the indentations in the side walls of each of the units of the heat exchanger will substantiallyincrease the heat exchange characteristics between'the products of combustion and the side walls of the heat exchanger. -Moreover, the indentations, in addition to the other features, pro- Y lvide an effective scrubbing actionl of the products of'combustion with the side walls vof the heat exchanger. Thus, 'it is apparent that a more 'uniform distribution lof the heat is effected to the heat exchange surfaces. Therefore, when air is vforced through the chambers y8G, 81| and 821, :the substantially even distribution of heat acrossthe heat exchange surfaces of Ithe respective Vunits of the .,:heat exchanger will substantially increase the @exchange of heat 'to the air which obviously results vin more eicient operation land saving .in Afuel costs.

Theheat exchanger contemplated herein `may be 'advantageouslyemployed in mass production :manufacturing methods. In this connection, the versatility of the heat exchanger in beingcapable of being manufactured in multiple units as desired 'to laccommodate various sizes and shapes of -furnaces will lresult in substantial economies of manufacture. In addition to this very important feature, the 'improved vheat exchanger contem- Lplated by this invention provides substantial 'increased eiciency of operation which will result in economies of operation. A,

From the foregoing disclosure, it -can be observed that I have provided an improved :heat :exchanger which efficiently fulfills .the objects thereof as hereinbefore set forth and provides numerous advantages which may Vbe ,summarized ,as .follows 61. .structurally simple, eiiicient and durable; y

'2. .Economical to manufacture and `readily :adaptable vto mass production manufacturing principles; and

B. The provision of a heat exchanger which maybe manufactured in any desired number of segments, thereby to increase the versatility of the-assembled heat exchanger in that various sizes and arrangements may be obtained to facilitate universal application of the 'teachings of this invention.

While I have illustrated a preferred embodiment of my invention, many modifications may be made vWithout departing from the spirit ofthe invention, and I do not wish to be limited to the precise 'details of construction set forth but Wish to avail myself of all `changes Within the scope L'of the appended claims. l

I claim:

"1. A heat exchanger for a warm air furnac comprising, a plurality of upstanding tubes lof substantially shallow flat rectangular contour with va pair of substantially iiat walls andarranged inparallel spaced relation to each other for'receiving the products of combustion froma 'heat source, said tubes being dened'by'a series vof sections, each section comprising a substantially flat U-shaped channel configuration land being bent A'back on itself to dene Ythe legs of `a second U-shaped configuration, 'one leg of said l 'last mentioned Y'U shaped configuration forming 'one-half of the shallow rectangular tube andthe other leg of said last Vmentioned U-shaped configuration forming Vone-half of the nextv adjacent shallow rectangular tube, said substantially flat Vcupped-,like deformations on the walls opposite vthe indentations of the rsame tube and in vtouch-- ing `relationship with said indentations to provide -spacersto holdsad walls of the respective tubes in proper spaced relation.

2. A hea'tl exchanger .for ;a Warm air furnace for receiving the products of combustion from a heat source comprising a series of sections being offlat channel shaped formation with aplurality of inward indentations extending substantially the depth of the region defined by the ychannels and substantially transverse the width of the channels, said channels being vbent back on them- Aselvesin a `U-shaped manner `and placed adja- -cent each other so that twosuccessive Vsections form walls of a tube open at its top and bottom ends, vthe opposingwalls of said tubes being continuously tapered toward each other to provide Aa larger opening at one end than at the other, said indentations being spaced along one `wallof the channel and successively alternated With "respect 'to Vthe indentation on the opposed Wall so as cto be spaced from the-opposed wall of the-other vchannel to `provide a serpentine vpath inthe tube for the products of combustion, and a plurality offcup-like inward deformations on the Wall directly opposite the indentations, said deforma- -tions meeting the latter substantially at the center line of the vtube to provide lspacers to hold the walls of the respective tubes in proper position.

3., -A heat exchanger for a warm air furnace forreceiving the products of combustion from Ya heat source comprising a series of sections being offlat channelshaped formation with va plurality of inward indentations extending substantially the depth of the region defined by the channels and substantially transverse the width of the channel, said channels being bent back on themselves in a U-shaped manner and placed. adja- .cent 'each other vso that two successive sections form walls .of Va'tube open at its top and bottom ends, the opposing Walls of said `tubes being continuously `tapered toward-each other to provide a -larger opening at one end than at the other, said indentations ybeing spaced along said fwalls and successively 'alternated so as to be .spaced 'from the opposed wall of .the other .channel to provide va serpentine 'path 4in lthe 'tube for the productsv .of combustion,a plurality of inward deformations Von the wall directly opposite the indentations, said deformations meeting the latter .substantially at the centerline of the tube `to provide `spacers `:to hold the YWalls Lof the respective tubes in proper position, and flanges on rone end of said bent 'back .sections in abutting relation with 'each Yotlierto provide proper .spacing between the re- .specitive :tubes lso 'as to denne a closed vfluid path .for the products vof combustion.

,4; A heat exchanger fora warm air 'furnace :for receiving the products of -combustion from 'a :heat source comprising a series of integrally formed substantially U-shape channel sections with .a 'relatively Wide `wall and two "relatively lnarrow `walls .formed at substantially right angles to vsaid wide Wall, said channel being bent back Von itself to provide .a U-,s'ha'ped configuration and placed .adjacent eachother so that 'two .successive sections denne shallow tubes, the Ywalls of yone opposed wall of the tube and thereby providing a serpentine path for the products of combustion from the heat source entering said larger opening of the tube, and cupped-like deforma- ,tions opposite said indentations, said cup-like deformations extending inwardly adepthso as to substantially meet the latter to' provide spacers to hold the walls ofthe respective tubes in proper spaced relationship.

5. A heat exchanger as claimed in claim 4 wherein each of the bent back sections is provided at one end with bent back anges in abut ting relationship to provide proper spacing between the sections so as to dene a closed uid path for the products of combustion.

l 6. A heat exchanger for a warm air furnace comprising a series of sections secured together to deiine a plurality of upstanding flat tubes of rectangular contour open at the bottom and top and arranged in parallel spaced relation to each other for receiving the products of combustion from a heat source, each section being dened by a. relatively shallow and relatively wide U-shaped channel being bent back on itself in a U-shaped manner and placed adjacent a, similar section so that two successive sections deiine the tube, onehalf of one section dening the walls of one-half of a rst shallow tube and the other half of said sectiondening the walls of one-half of a'second shallow tube, a plurality of indentations substantially transverse said side walls and extending inwardly of each tube wall, said indentations being spaced along the Walls and successively alternated so as to be spaced from the Walls of the opposed Wall of said tube thereby providing a serpentine path in the tube for the products of combustion, the opposing walls of each tube being continuously tapered toward each other in an upward direction to provide a larger opening at the bottom than at the top, and cuplike vdeformations extending inwardlyA to meet some of said indentations to provide spacers to hold the Walls of the respective tubes in proper position.

KENDALL H. FLINT.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS France Jany3. 1907 

